NIOSHTIC-2 Publications Search

Synthetic fluorspar for conditioning electric furnace slags.

Nafziger-RH; Blake-HE Jr.
U S Pat 4 053 302 1977 Oct; :
A calcium fluoride-containing composition for use in conditioning electric furnace steelmaking slags is prepared from byproduct scrubber solutions derived from wet-acid processing of phosphate rock by reacting the scrubber solution with calcium hydroxide. Thus, the scrubber solution consisted of an aqueous solution of h2sif6, ca(h2po4)2, and h3po4 and contained about 85 g/l of h2sif6 and 28 g/l of p2o5. 50 L of this solution was heated to 65 deg c and 8,800 g of powdered ca(oh)2 was added slowly and with vigorous stirring to provide a slurry having a ph of 9. The temperature was maintained, and the slurry stirred, for a period of 60 min, after which the resulting precipitate was separated by filtration and dried at 100 deg c for 12 h. The resulting composition, containing 54.4 Wt pct caf2, 10.6 Wt pct sio2, and 11.2 Wt pct p2o5, was then employed as a slag conditioner in a steelmaking process in which 1,431 lb of scrap iron, was melted in a 1-ton electric furnace under 41 lb of a slag consisting of 25 lb pebble lime and 16 lb quartz (basicity 1.5), Followed by slag removal and treatment with 58 lb of a more viscous slag containing 39 lb pebble lime and 19 lb quartz (basicity 2.25). After this slag was molten, 16 lb of the prepared slag conditioner was added and heating continued for 47 min. Samples were taken periodically, and the slag conditioner was found to reduce slag viscosity. At the end of the test, the metal product was found to have reductions in impurity levels as follows: 0.018 to 0.007 Wt pct p, 0.23 to 0.03 Wt pct c, 0.010 to 0.008 Wt pct s, 0.30 To <0.
Publication Date
Document Type
Fiscal Year
Identifying No.
PAT 4,053,302
NIOSH Division
Source Name
U.S. Pat. 4,053,302, Oct. 11, 1977, Chem. Abstr. Not Found
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division